1. Field of the Invention
The invention relates to a proton conductor, and a fuel cell and a fuel cell system that include the proton conductor.
2. Description of the Related Art
A fuel cell is a device that produces electric energy typically using hydrogen and oxygen as fuel. The fuel cell is advantageous in terms of environmental protection and achieves high energy efficiency. Therefore, the fuel cell is widely developed as a future energy supply system.
A proton conductor is developed as an electrolyte membrane used in the fuel cell. For example, Japanese Patent Application Publication No. 2005-276721 (JP-A-2005-276721) describes the technology in which a solid acid is used as the proton conductor.
However, some types of solid acids are water-soluble. In this case, the electrolyte may be dissolved by water produced by a power generation reaction that takes place in the fuel cell.